Highly available particulate controlled release nitrogen fertilizer

a technology of nitrogen fertilizer and controlled release, which is applied in the direction of material granulation, granulation in rotating dishes/pans, biocide, etc., can solve the problems of increasing the osmotic pressure, or osmolality, of the fertilizer, and difficulty in granulation of urea containing solids, etc., to achieve high nitrogen conversion, low hot water insolubility, and high single season nitrogen efficiency

Inactive Publication Date: 2000-04-11
AGRINUTRIENTS TECH GRP INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

An even better combination of high conversion of nitrogen to controlled release and high single season nitrogen efficiency or low hot water insolubility is obtained when the mol ratios of formaldehyde, urea, and ammonia are held in the narrow range between 1 to 1.70 to 0.03 and 1 to 1.80 to 0.10.
The formaldehyde and a minor portion of the urea may be advantageously provided as a urea formaldeh

Problems solved by technology

Although the low HWIN is desirable, the high free urea is not because it increases phytotoxicity of the fertilizer significantly, and causes severe granulation difficulties by creating sticky operating conditions.
A high process recycle ratio and low process temperature must be used to granulate fertilizers containing high free urea contents because very small amounts of water cause urea containing solids to become sticky and difficult to granulate.
The amount of ammonia required and the anion required to neutralize it, undesirably increased the osmotic pressure, or osmolality, of the fertilizer.
Increasing osmolality has been shown to increase the phytotoxicity of a fertilizer.
When the CWIN is not soluble in hot water, it is known that the nitrogen is unavailable for plant u

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

This example is provided to demonstrate a preferred method of preparing granular nitrogen fertilizers containing substantially controlled release nitrogen which exhibits high CRE (controlled release efficiencies) and single growth season availabilities.

To an enclosed stainless steel 304 reaction kettle equipped with a heating and cooling internal coil and jacket, a reflux condenser, mixing agitator, and a circulating pump was added in the order listed the following ingredients:

The liquid mixture containing formaldehyde to urea to ammonia in a mol ratio of 1 to 1.75 to 0.1 exhibited a pH of 8.6 and was heated to a temperature of 90.degree. C. at one atmosphere (760 mm Hg) pressure for a period of time amounting to 45 minutes with constant agitation, and with the reflux condenser returning all condensate derived from evaporation to the kettle. At the end of the 45 minutes reaction period analyses showed zero free formaldehyde, 0.03 percent free ammonia, and 3.02 percent urea nitrogen....

example 2

This example is provided to demonstrate the safety from phytotoxicity and the efficacy of the preferred granular fertilizer composition of the instant invention. Osmolality has been shown in the art to be an accurate indicator of phytotoxicity of nitrogen fertilizers with increasing osmolality (osmotic pressure of aqueous fertilizers) indicating increasing phytotoxicity. Osmolalities were measured at the 3 percent nitrogen level in water from the product of Example 1 and various other nitrogen fertilizers for comparison. These results are tabulated as follows:

To evaluate the availabilities to plants in soil of the nitrogens in several controlled release products, the products were applied to a plot growing Kentucky Bluegrass, at the rate of 3 pounds of nitrogen per 1000 square feet, and the soil was sampled through a single growing season in the laboratory at ambient temperature to determine the amount of unmineralized nitrogen remaining in the soil. The results are tabulated as fol...

example 3

This example is provided to demonstrate a perferred method of preparing particulate complete NPK fertilizers containing substantially controlled release nitrogen which exhibits high controlled release efficiencies.

Using the enclosed stainless steel reaction kettle of Example 1, the following ingredients were added in the order listed:

The liquid mixture exhibited a pH of 8.3 and was heated to a temperature of 91.degree. C. at 745 mm Hg pressure for a period of time amounting to 35 minutes. Analysis showed zero free formaldehyde, 0.01 percent free ammonia, and 3.61 percent urea nitrogen.

The dehydrating reactor of Example 1 was preheated to a temperature of 90.degree. C., and the liquid mixture was charged thereto, and 3.75 kilograms of 40 percent P.sub.2 O.sub.5 orthophosphoric acid dehydrating catalyst was added over a 30 second period to bring the pH of the mixture to 3.0 to initiate the dehydration-condensation reaction. The exothermic reaction increased the temperature in the reac...

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Abstract

A method preparing controlled release nitrogen in particulate fertilizers which exhibit single growing season availabilities to plants of about 80 percent or higher. The method utilizes relatively low urea and ammonia to formaldehyde mol ratios of about 1.7 urea to 0.1 ammonia to 1 formaldehyde to assure high conversions to controlled release nitrogen with low free ureas, and carefully controlled elevated temperatures, acid dehydration condensation catalyst concentrations and short dehydration reaction times of about 2-4 minutes to provide effective conversion of hydroxymethyl nitrogen compounds by dehydration condensation reaction to controlled release methylene nitrogen compounds. Quick neutralization of the dehydration catalyst in a turbulent mixing reactor minimizes the formation of undesirable methylene nitrogen polymers which are hot water insoluble and unavailable to plants in a single growing season.

Description

1. Field of the InventionThis invention relates to controlled release nitrogen fertilizers and methods for their preparation. More particularly, the present invention is directed to a method of forming a new highly available slow release nitrogen fertilizer by condensing ammonia, urea, and formaldehyde under mildly basic conditions and elevated temperatures and then dehydrating the condensate without substantial polymerization to a controlled release solid fertilizer by means of a weak acid catalyst at elevated temperatures and short reaction times. The method provides granulation of homogeneous solids in a high intensity reactor either as a controlled release nitrogen, or complete N-P-K fertilizer. The new composition provided by this method provides higher nitrogen availabilities in high controlled release nitrogen concentrations than heretofore available.2. Description of Related ArtUreaformaldehyde condensation and polymer products are widely used as slow release nitrogen fertil...

Claims

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Application Information

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IPC IPC(8): C05C9/00C05C9/02C08G12/00C08G12/12B01J2/14C05G3/00B01J2/00
CPCC05C9/02C05G3/0047C08G12/12C05G5/40
Inventor MOORE, WILLIAM P.
Owner AGRINUTRIENTS TECH GRP INC
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